The patch titled Avoid divides in BITS_TO_LONGS has been added to the -mm tree. Its filename is avoid-divides-in-bits_to_longs.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: Avoid divides in BITS_TO_LONGS From: Eric Dumazet <dada1@xxxxxxxxxxxxx> BITS_PER_LONG is a signed value (32 or 64) DIV_ROUND_UP(nr, BITS_PER_LONG) performs signed arithmetic if "nr" is signed too. Converting BITS_TO_LONGS(nr) to DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) makes sure compiler can perform a right shift, even if "nr" is a signed value, instead of an expensive integer divide. Applying this patch saves 141 bytes on x86 when CONFIG_CC_OPTIMIZE_FOR_SIZE=y and speedup bitmap operations. Signed-off-by: Eric Dumazet <dada1@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/bitops.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN include/linux/bitops.h~avoid-divides-in-bits_to_longs include/linux/bitops.h --- a/include/linux/bitops.h~avoid-divides-in-bits_to_longs +++ a/include/linux/bitops.h @@ -6,8 +6,8 @@ #define BIT(nr) (1UL << (nr)) #define BIT_MASK(nr) (1UL << ((nr) % BITS_PER_LONG)) #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) -#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_LONG) #define BITS_PER_BYTE 8 +#define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) #endif /* _ Patches currently in -mm which might be from dada1@xxxxxxxxxxxxx are origin.patch avoid-divides-in-bits_to_longs.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html